Glossary
Percentile
The value below which a given percentage of observations falls. The 50th percentile is the median, the 25th is the lower quartile, and the 75th is the upper quartile. Percentiles are useful for describing the position of an observation relative to the rest of the distribution.
Definition
The value below which a given percentage of observations falls. The 50th percentile is the median, the 25th is the lower quartile, and the 75th is the upper quartile. Percentiles are useful for describing the position of an observation relative to the rest of the distribution.
Why It Matters
Percentiles give a clearer picture of a distribution than the mean alone, especially for skewed data. In education, healthcare, and economics, percentile-based benchmarks (such as growth charts or income percentiles) are the standard way to communicate where an individual or observation stands relative to a reference population.
Example
A university reports that a student scoring 680 on an entrance exam is at the 85th percentile, meaning the student performed better than 85% of all test-takers. This communicates relative standing more intuitively than the raw score alone.
Related Terms
Software Notes
- SPSS: Analyze > Descriptive Statistics > Frequencies; check "Percentiles"
- R:
quantile(x, probs = c(0.25, 0.5, 0.75)) - Stata:
centile variable, centile(25 50 75)